Polymer- Modifi ed Mesoporous Silica Thin Films for Redox- Mediated Selective Membrane Gating

Controlling structure and function to switch ionic transport through synthetic membranes is a major challenge in the fabrication of functional nanodevices. Here we describe the combination of mesoporous silica thin films as structural unit, functionalized with two different redox-responsive ferrocene-containing polymers, polyvinylferrocene (PVFc) and poly(2-(methacryloyloxy)ethyl ferrocenecarboxylate) (PFcMA), by using either a grafting to, or a grafting from approach. Both mesoporous film functionalization strategies are investigated in terms of polymer effect on ionic permselectivity. A significantly different ionic permselective behavior can be observed. This is attributed to different polymer location within the mesoporous film, depending on the functionalization strategies used. Additionally, the influence of chemical oxidation on the ionic permselective behavior is studied by cyclic voltammetry showing a redox-controlled membrane gating as function of polymer location and the pH value. This study is a first step of combining redox-responsive ferrocene-containing polymers and mesoporous membranes, and thus towards redox-controlled ionic transport through nanopores.